The disk cartridge of the prior art is comprised of a cartridge body made up of an upper half and a lower half abutted and connected to each other, and a circular disk rotatably accommodated within the cartridge body. Approximately at the center of the upper and lower sides of the disk-accommodating cartridge body, there are formed table insertion apertures confronted by a disk table of a disk driving device adapted for driving the disk into rotation and the pickup apertures confronted by a pickup writing or reading information signals to or from the disk, said pickup apertures being contiguous to said table insertion apertures and extending along the disk radius. A channel-shaped sliding shutter for opening or closing the table insertion apertures and the pickup apertures is adapted to be press-fitted from the front side of the cartridge body.
The sliding shutter is so designed that, when it is in the cover-closed position covering the pickup apertures, the bent portion provided to the shutter as the locked member is locked by engagement with a locking recess in a locking member provided to the cartridge body in such a manner as to prevent dust deposition on or injury to the disk accommodated in the cartridge body otherwise caused by inadvertent opening of the pickup apertures.
It may be contemplated to effect a cover-opening operation of the sliding shutter by a sliding operation after the bent portion to be locked is disengaged from the locking recess by resilient deflection of the locking member caused by an unlocking pin provided to the recording and/or reproducing device operatively connected to the disk cartridge.
In the disk cartridge wherein unlocking is performed in the aforementioned manner, the amount of deflection of the locking member is changed with the position acted upon by the unlocking pin of the locking member. As a result, the thrust force applied to the resilient deflecting portion of the locking member which is designed with a predetermined resilient deflection is drastically changed so that a load in excess of the limit of mechanical strength may be applied to the resilient deflecting part thus occasionally causing destruction of the locking member. Even though the resilient deflecting part is not destructed in this manner, the locking function proper to the locking member is lost as a result of application of a load in excess of the threshold strength value. As a result, the pickup apertures are opened through inadvertent opening of the shutter resulting in destruction of the disk contained in the cartridge body through intrusion of dust and dirt or other impurities.
It is therefore an object of the present invention to provide a disk cartridge wherein an unnecessary load is not applied to the shutter locking member except during the opening or closing operation for thereby assuring sufficient resilient deflection for a prolonged time, and wherein inadvertent cover-opening operation of the shutter is prevented to assure positive disk protection by providing a positive shutter locking.
It is another object of the present invention to provide a disk cartridge in which a passage for a bent portion of the shutter is provided in the shutter locking member is an engaging recess of which said bent portion to be locked is engaged to lock the shutter.